>>508859004 (OP)>Multiculturalism would've worked had everyone been genetically homogenous.Racism is a naturally evolved adaptive trait which confers a survival advantage to those which express it strongly. The more diversity, the more of a plethora hardships mount up. Foreign disease, low social ties, maladaptive foreign genetics and environment, maladaptive foreign culuture, among many others. Ultimately, when pressed together, genetically different groups of humans will turn to war.
Not only doesn't multiculturalism work, multiethnicism is a disaster.